<hi style=afpcap>The O-46 design was a variant of the O-43 which Douglas produced with the fitment of a 725 h.p. twin-row Pratt and Whitney R-1535-7 engine. Production versions of the O-46A differed from the prototype XO-46 with rear fuselage built up between the cockpit and the tail in a similar to the O-31B.</hi>